Questions from a disc brake noob

I ride a 2005 Trek 6500 with V-brakes. I recently got a free upgrade to a Recon 351 coil fork, so I took the offer. The only problem was it is a disc brake only fork. I decided I might as well upgrade both rear and front v-brakes to disc, so I ordered two Avid BB7's with 185mm rotors. This is before I realized people usually put a smaller rotor on the back than the front, and that 160mm calipers probably would have been more than enough stopping power.

Is there any problem with putting the larger 185mm (7 inch) rotor on both front and rear of my bike? I'm assuming the fork can handle the extra torque since I believe it can handle a 203mm rotor max. Will my frame be alright with the larger rotor in the rear? I'm 6'1" about 180lbs. Is there any other issues or problems I should consider? Oh, and if it came to it, is it possible to use a smaller rotor with the calipers that came with the 185mm or do you need to buy a caliper meant for a 160mm rotor? Sorry if some of these questions are dumb, haha. Thanks guys! I appreciate all the help I've received from this forum.

No worries putting a 185mm rotor on the back, as long as the frame can fit it. If there's a clearance issue, usually it's at the chainstay. I'd measure the clearance, allowing for a bit more because you'll need extra to fit the wheel into the dropouts. Better yet, since you have the rotors already anyway, just throw it on and see if it'll fit.

The calipers are meant for all sizes of rotor, you just have to use the right adapter for a given rotor size.

okay yeah, I checked and it seems like there will be no clearance issues. I'm having the LBS install the new fork, should I have them put the disc brakes on as well? I don't know much about them so I don't want to screw something up haha.

Yeah I have worked on Vbrakes. The only reason I am weary of doing it myself is I ruined a couple things when I took it upon myself to take them apart, put them together, haha. Usually caused by over-torquing. Oops! I've learned from my mistakes though.

Anything else I should know about disc brakes? What do people mean when they talk about 'bedding' the pads in?

Bedding the pads in = breaking in the pads and rotors. After a few hard stops, the brake's power will improve. Nothing special you need to do, just go out and ride knowing that the brakes may feel a little weak at first, but the power will come on strong later.